Evidence suggests that there is a strong genetic component in the population variation of personality traits. A recent approach to identifying the genetic basis of this personality variation has involved associating the presence of a particular allele at a polymorphic site with increased or decreased scores on a personality factor scale. Two of the first positive findings, using this sort of design, were an association between a serotonin transporter polymorphism and Neuroticism and between a dopamine 4 receptor polymorphism and Novelty Seeking. Unfortunately, attempts to replicate these two associations have produced conflicting results. Our project is intended to a) explore these associations with a study design that addresses the problem of previous studies b) explore a possible association between DRD4 and alcohol use and c) explore the possibility of a novel association between polymorphisms in the Brain-Derived Neurotrophic Factor Gene (BDNF) and Neuroticism. The overarching hypothesis guiding this project is that polymorphisms within genes involved in neurotransmitter systems are, in part, responsible for the variation in personality traits in the population being studied. We have collected DNA samples from 450 subjects who have completed the NEO-PI self-assessment questionnaire. We will assess whether there is an association between each genotype and the relevant personality trait. Through these studies, we hope to learn more about the role of these genes in personality trait variation.